Magnesium sulfate is a medication that has been in sidespread use in the management of two common complications of pregnancy: 1) Preeclampsia - a high blood pressure problem of pregnancy and 2) Premature labor - labor which occurs early, before the baby is full term. Although sidely used, there is little known about the pharmacokinetics of the drug for premature labor. There is also little comparison of the drug's effect in preeclampsia and premature labor. This study seeks to systematically study the pharmacokinetics of magnesium in preeclampsia, preamture labor as well as describe the free magnesium levels along side the standard total magnesium levels.